Is Eyewitness Testimony Inherently Unreliable?

By Aileen P. Clare – May 28, 2012

To those who follow crime and courts, the stories are familiar and unnerving. Cornelius Dupree spent 30 years imprisoned in Texas for a 1979 rape and robbery he did not commit, largely due to a single eyewitness identification. He was freed in 2011 through new DNA evidence. Derrick Williams of Florida was freed through DNA evidence after spending 18 years in prison for a rape based on eyewitness misidentification. Johnny Pinchback, a Texas inmate convicted of a 1984 rape based on eyewitness misidentification, was freed through DNA testing after 27 years in prison. Alvin Jardine was freed through DNA testing after serving 20 years jailed in Hawaii, again due to eyewitness misidentification. Of the 21 cases on the Innocence Network’s 2011 exoneration report, 19 wrongful convictions involved eyewitness testimony. Innocence Network Report, 2011. This is consistent with statistics showing that more than three-quarters of wrongful convictions later overturned by DNA evidence relied on faulty eyewitness evidence.

Even after hearing the statistics, we are reluctant to distrust a sincere eyewitness, but decades of research show that memory is neither precise nor fixed. For instance, we would expect a moment of high stress to focus the mind and sharpen recall, but the opposite is true. Violence, stress, and the presence of a weapon during an incident actually weaken memory. Racial differences between the witness and the suspect can impair identifications. Unconscious transference, or confusing someone seen in one place with someone seen in another place, is common. Identification can also be impaired by how long the witness is exposed to the suspect, the delay between the incident and the identification, and post-event information, such as feedback from the police or other witnesses.

Our evidentiary system presumes the reliability of eyewitness testimony unless it has been tainted by official action. Jurors, too, are mostly “not sensitive to the malleability of human memory” and tend to over-credit eyewitnesses. The challenge for criminal-justice systems is twofold: at the front end, minimizing circumstances that corrupt eyewitness accounts, and, at the trial stage, giving the jury the information it needs to critically assess the evidence.

System Variables: Things the Criminal-Justice System Can Control
In a recent watershed opinion, the New Jersey Supreme Court, after reviewing a special master’s record of 300 exhibits, including 200 scientific studies, thoughtfully divided the factors affecting eyewitness evidence into two categories: system variables and estimator variables. State of New Jersey v. Henderson, 27 A.3d 872 (N.J. 2011).

System variables are things that can be controlled by the criminal justice system. The predominant system variable is the photographic or physical lineup. Studies show that witnesses select the wrong suspect from a photo lineup roughly a quarter of the time. When the suspect is left out of a lineup, witnesses pick an innocent person more than a third of the time—even when told that the suspect may not appear in the lineup.

Lineups are responsible for many misidentifications, but there are practical steps that a law-enforcement agency can take to minimize error, and for litigants, the absence of these steps can raise a red flag.

Lineups should be blind or double-blind, meaning that the officer administering the lineup does not know who the suspect is. This removes the danger of unintentional suggestion. The officer should emphasize that the suspect may not appear in the lineup. The witness should not feel obligated or pressured to pick anyone.

Of course, lineups should be constructed so that the suspect does not stand out. Photos should have similar lighting, and headshots should be the same size. Errors tend to increase when there are too many photos to choose from; the optimal number seems to be six. Two suspects should not appear in the same lineup. Multiple viewings of the same suspect should be avoided.

The police should carefully avoid post-identification feedback or confirmation, which can create a false sense of confidence in a witness. If a witness hears that he or she did a “good job” picking a certain face, even the wrong one, she is more likely to repeat the mistake at trial. For the same reason, multiple witnesses to the same event should be told not to discuss the identification procedure among themselves.

“Show-up” identifications, where the police produce a single suspect for identification, are inherently suggestive, although sometimes necessary. The accuracy of a show-up identification diminishes quickly following an event, so show-ups should be used, if at all, within two hours of the event.

Estimator Variables: Things the System Can’t Control
Estimator variables are things that are beyond the control of the criminal justice system but can affect a person’s ability to perceive and recall.

A person under high psychological stress at the time of an event is less likely to make a reliable identification later. Studies of eyewitnesses, including one controlled study of military personnel, consistently show that high stress impairs recall and identification.

When a weapon is present during an event, it can distract the witness’s attention away from the suspect and lead to poor descriptions and misidentification later, especially when the event has a short duration. Weapon focus has been shown to decrease the accuracy of identifications by about 10 percent.

Other proven estimator variables reflect conventional wisdom. Distance, lighting, and how long a witness had to view the suspect are all important, as are the witness’s personal characteristics, such as age, race bias, or level of intoxication. Personal characteristics of the suspect, even something as simple as wearing a hat or different facial hair, have been shown to affect identifications.

Memory decay is inevitable and irreversible. The more time that passes between the event and the identification, the more likely a witness is to misidentify or fail to recall a suspect. This is an estimator variable, but the system can minimize its effect by staging identifications as soon as possible after the event.

Who Gets a Suppression Hearing? What If You Don’t?
The Supreme Court set the standard for suppressing eyewitness identification in 1977. Manson v. Brathwaite, 432 U.S. 98 (1977). It has remained virtually unchanged since then.

Under Manson, the court may grant a pretrial suppression hearing on identification if the defendant shows that the police used a suggestive identification procedure, such as showing the witness a single photograph of the defendant instead of a neutral photo lineup. At the hearing, the court weighs the “corrupting effect” of the suggestive procedure against factors affecting reliability: the witness’s opportunity to view the suspect, the degree of attention, the accuracy of description, confidence during the identification process, and the time between the event and the identification. The evidence should be suppressed only if there is a “very substantial likelihood of irreparable misidentification.”

Henderson modified this test for New Jersey courts. A New Jersey defendant still needs to show suggestiveness to get a suppression hearing, but he or she does not need to show that it resulted from police action. The state must respond with proof that the identification is reliable, taking into account system and estimator variables. The defendant bears the burden of proving misidentification. The court should suppress the evidence if it finds from a totality of the circumstances that there is a very substantial likelihood of irreparable misidentification. If the evidence is admitted, the judge should give the jury specific instructions grounded in science.

Several months after Henderson, the Supreme Court weighed in. In Perry v. New Hampshire, 132 S.Ct. 716 (2012), the Court reaffirmed Manson’s rule that the defendant must make a threshold showing of suggestive police action before getting a suppression hearing. Suggestive action by private actors, or the presence of other “corrupting” influences, does not warrant suppression as a matter of constitutional right.

It appears defendants outside of New Jersey may still have to show suggestive police action to suppress eyewitness evidence, but Henderson’s analysis and conclusions can inform the rest of us.

Educating the Jury
The Constitution, Perry said, protects against wrongful convictions not by barring questionable evidence, but by giving the defendant “the means to persuade the jury that the evidence should be discounted as unworthy of credit.” Although Perry reaffirmed the narrow suppression threshold, it acknowledged the high incidence of misidentification and encouraged defendants to challenge unreliable eyewitness testimony through the traditional means of cross-examination and compulsory process. Additionally, it said, defendants can move for exclusion on the non-constitutional ground that the evidence’s prejudicial effect outweighs its probative value.

Rules of evidence generally permit expert testimony if it will assist the jury and if it represents valid scientific or technical knowledge. Some courts are resistant to expert testimony on eyewitness identifications, questioning its scientific basis and perceiving it as an intrusion on the jury’s traditional role of weighing witness credibility. E.g.,United States v. Rodriguez-Berrios, 573 F.3d 55 (1st Cir. 2009); United States v. Smith, 122 F.3d 1355 (11th Cir. 1997). Five states—Kansas, Louisiana, Nebraska, Oregon, and Pennsylvania—have categorically excluded expert testimony on misidentification, but a substantial and growing number of jurisdictions are open to this kind of testimony where it is reliable and relevant. Ferensic v. Birkett, 501 F.3d 469 (6th Cir. 2007); United States v. Brownlee, 454 F.3d 131 (3rd Cir. 2006).

Regardless of jurisdiction, defendants can cite Henderson and the studies it cites for the proposition that scientific research on eyewitness evidence is now established and reliable. If relevant, expert testimony on this science should be among the devices that Perry promotes as safeguards against wrongful conviction.

Additional Reading
The Henderson court reviewed the law and science as well as any law review could, but for further reading, especially on the admissibility of expert evidence on this topic, see:

George Vallas, “A Survey of Federal and State Standards for the Admission of Expert Testimony on the Reliability of Eyewitnesses,” 39 Am. J. Crim. L. 97 (2011);